Intermediate shafts are typically comprised of two main components: a tubular sub-assembly and a solid shaft sub-assembly. This combination allows for telescoping of the intermediate shaft so that it may be installed in a car, and potentially collapse during a crash scenario.
The solid shaft sub-assembly is traditionally made by an interference fit between a solid shaft and a yoke. The interference is typically created by forming a serration on the yoke, and forming a complimenting but slightly different serration on the solid shaft. These slightly differing serrations create an overlap of the serration flanks on the yoke to the serration flanks on the shaft. This connection holds together the yoke and shaft so that they may form the solid shaft sub-assembly.
Some solid shaft sub-assemblies may undergo a “staking” operation to add an axial retention feature after the yoke and shaft are pressed together. This feature or “stake” is a small patch of metal on the solid shaft that is deformed past the original outer diameter.
However, with some known solid shaft sub-assemblies, the serrations may be difficult to design, difficult to manufacture, and may be easily damaged. Additionally, the interference connection may be limited in the axial retention force it can withstand before failing. Because of this limited retention force, a redundant axial retention feature is required. Traditional solid shaft sub-assemblies may also encounter difficulties during assembly. For example, the required load to press the two components together may be too high or too low, the components may not press together on a parallel path, the serrations of the components may not connect as desired, or the components may not press together for the desired distance. Accordingly, it is desirable to provide an improved solid shaft sub-assembly.